1. Field
The embodiments relate to Internet Protocol (IP) Private Branch Exchange (PBX), and more particularly to non-centralized distributed IP PBX complete platforms.
2. Description of the Related Art
Office PBX has always been a standalone centralized system entity, dating back to the “switch” concept in Public Switched Telephone Network (PSTN), where a centralized switch/system is responsible for receiving, connecting, and distributing telephone calls inside an office building over time-division multiplexing (TDM) circuits connected to it. With the advent and proliferation of IP networks in the enterprise, a new breed of PBX has emerged, IP PBX, which performs the same functionality as the traditional TDM/PSTN PBX but operating on top of the IP network using Voice over IP (VoIP) technology.
IP PBX, however, inherited the same centralized control model of the TDM/PSTN PBX and is implemented in the form of a centralized system (more specifically, the combination of an application server and a media server, often co-located in the same platform, with additional servers handling centralized control functions). FIG. 1 illustrates a centralized IP PBX system. System 100 includes enterprise IP network 101 that includes application server 105, interactive voice response (IVR) server 110, presence server 115, conferencing server 120, session initiation protocol (SIP) registrar 125, SIP proxy 130, SIP redirect server 135, and SIP electronic number mapping (ENUM) server 140. Connected to enterprise IP network 101 are multiple SIP clients 150 and personal computer (PC) soft clients 155.
A centralized system has a numerous disadvantages, including the introduction of a single point of failure in the enterprise telephony system and the inability to scale in density, etc. IP PBX systems, in particular, suffer from their severe density limitations and scale very poorly, due to the media processing bottleneck in the centralized servers.